.223 Twist Rate

[HammerForged]

My Tikka action is at Preferred Barrels awaiting a new barrel. I went with a 24" heavy palma. I want to be able to shoot match grade heavier ammo as primary, but still shoot regular, off the shelf .223 if match grade gets scarce.

My question: is a 7.5 twist rate good? Any recommendations from .223 shooters. I ordered 7.5 but I have a few weeks to change it. This is a range gun, not a hunting rifle.

Thanks Hide!
C King

PS, I brought my action to them in person and they were great! I even got a tour of the facility and saw how the sausage is made.

 

[oldrifleman]

1/7 or 1/7.5 are great for longer bullets

 

[Potsy]

I’d 7.

 

[gopherslayer]

7

 

[Jgault]

All of mine are 7 and have one 8, 7 seems to be a little more accurate with 60+ grains and 8 better with 55 grains, but the difference is pretty minimal, unless I’m on a bench with a bipod or bag really can’t tell a difference.

 

[redbullitt]

Unless you're shooting very light varmint stuff I think a 7 twist is perfect. 7 has done fine with anything I shoot from 62g greens up 77 tipped and 77 smk.

 

[stello1001]

Seven

 

[6BRABlackbear]

I run 90’s with 7 and 6.5 twists. Both work well. 7.5 should be fine with 77’s. Berger website has a twist rate calculator.

 

[tomme boy]

223 seems to do best with a 8 twist for most bullets. My last barrel I went back to a 9 twist as I mainly shoot 50-60gr bullets only. The frthest I shoot is 300yds anymore.

 

[kentuckyMarksman]

I'd go with a 7" twist.

 

[roostercogburn98]

I have a 1-7.7 twist and it shoots pretty decent

 

[sierracharlie338]

You’d be fine with a 7.5 but if you plan to shoot any of the heavies 80+ then I’d go 7.

 

[Mauser48]

I am running a 7 twist and shoot 77 smk and 80 smk. The 80 smk are running at 2810 fps which is right about 289k rpm. My barrel is a 24" Bartlein. @Frank Green id love to get your take on this. I believe I've heard you say in the past you want to stay under 300k rpm. If I had something like a 28" barrel where the velocity would be about 100 fps faster would a 7.5 twist be more appropriate?

 

[Potsy]

I’m no Frank Green, but one thing I would add (and I think I’ve read Frank’s comments on this), is I would probably run 5R rifling along with the 1:7” twist.
There is some consensus that 5R is a bit “kinder” to jackets on their way down the barrel.
My .22BR barrel is a ‘Bart 1:7” 5R, and it is still spooky accurate (for me) with 75 ELD’s at 3,150fps (well over 300K) after several hundred rounds down the pipe.

 

[Mauser48]

I’m no Frank Green, but one thing I would add (and I think I’ve read Frank’s comments on this), is I would probably run 5R rifling along with the 1:7” twist.
There is some consensus that 5R is a bit “kinder” to jackets on their way down the barrel.
My .22BR barrel is a ‘Bart 1:7” 5R, and it is still spooky accurate (for me) with 75 ELD’s at 3,150fps (well over 300K) after several hundred rounds down the pipe.

I remember reading that as well. My barrel is also 5r and it shoots extremely well. I'd venture to say the jackets on these heavier match bullets is tougher as well compared to the lighter varmint bullets.

 

[Frank Green]

I am running a 7 twist and shoot 77 smk and 80 smk. The 80 smk are running at 2810 fps which is right about 289k rpm. My barrel is a 24" Bartlein. @Frank Green id love to get your take on this. I believe I've heard you say in the past you want to stay under 300k rpm. If I had something like a 28" barrel where the velocity would be about 100 fps faster would a 7.5 twist be more appropriate?

The 7.5 twist won't hurt ya. That's for sure. So if you go to 2910fps in a 7.5 twist... that puts you at 279,360rpm.

2910fps in a 7 twist.... that gives you 299,314rpm. You will be on borrowed time.

Again as you approach 300k and especially you start going past 300k... expect problems. Might not be at first but as soon as that throat area of the chamber starts getting rougher... the bullets will take more of a beating and the faster rpm isn't going to help anything. Some bullets might stand up to it and some might not. Again your on borrowed time.

Longer barrel... also generates more heat on the bullet due to friction... another factor that will play into it as well.

 

[Frank Green]

I remember reading that as well. My barrel is also 5r and it shoots extremely well. I'd venture to say the jackets on these heavier match bullets is tougher as well compared to the lighter varmint bullets.

some are and some are not / jacket wise thicker on the heavy bullets.

That being said.... and I'm not poking at any given bullet maker but one makers heavy bullets still had a high failure rate. The jacket needs to be redone.. I don't know if they done it or not at this point in time.

 

[Frank Green]

I’m no Frank Green, but one thing I would add (and I think I’ve read Frank’s comments on this), is I would probably run 5R rifling along with the 1:7” twist.
There is some consensus that 5R is a bit “kinder” to jackets on their way down the barrel.
My .22BR barrel is a ‘Bart 1:7” 5R, and it is still spooky accurate (for me) with 75 ELD’s at 3,150fps (well over 300K) after several hundred rounds down the pipe.

Correct.... the odd number of lands don't directly oppose one another which helps distort/upset the bullet jacket less which induces less stress on the jacket.

Also in testing in Aug. 2022 done by a ammo/bullet maker.... they found that at extreme pressures/velocities.... the 5R didn't create a burr on the side of the bullets jackets. Even on solids. VS an even number groove barrel. What happen here was the BC of the bullets out of the 5R rifling where more consistent. That burr on the bullets from the 6 groove rifling in this test compromised the bc of the bullet as much as 5%. You won't see it per se at short range but start getting out to 500 yards and further and it will show on the target with bigger groups. I seen pictures of the bullets taken right after they left the barrel. 320 rounds fired total and every bullet out of the 6 grooves had the burr. Not a single one out of the 5R had it. 12 barrels tested in total. 7 of them had saami spec. 6 groove rifling and 5 of the barrels had 5R rifling. At the time I didn't know anything about the test and that we made all the barrels. The info was shared with me about a month or two after the test was run. The burr on the side of the bullet was as big as a 1/32" or if you will .031".

Big Army and Hornady ran into the same thing the same year about 7 years ago in testing at 1k and 1200 yards. Each place didn't know the other one was doing testing and what they found by accident. In Hornady's case testing 6.5CM stuff and one barrel was a 4 groove we made them and the other 5R rifling. Army had 5R and Saami spec 6 groove barrels if I recall correctly. Anyways what they found was all of the bullets fired out of the 5R rifling... bullets flew more consistent because the bc of the bullet wasn't being effected. This confirmed what happen in the Aug. 2022 test. Now we know what Hornady and Army was seeing several years back but couldn't figure out why.

 

[SnowMan]

I have a Rem 700 with a 24"/1-8 twist Krieger. The biggest bullet I tried was a 77g Berger. It seemed to do ok.

 

[Mauser48]

The 7.5 twist won't hurt ya. That's for sure. So if you go to 2910fps in a 7.5 twist... that puts you at 279,360rpm.

2910fps in a 7 twist.... that gives you 299,314rpm. You will be on borrowed time.

Again as you approach 300k and especially you start going past 300k... expect problems. Might not be at first but as soon as that throat area of the chamber starts getting rougher... the bullets will take more of a beating and the faster rpm isn't going to help anything. Some bullets might stand up to it and some might not. Again your on borrowed time.

Longer barrel... also generates more heat on the bullet due to friction... another factor that will play into it as well.

Thanks Frank. Great information as always. It seems like the F class and benchrest guys lean towards the least amount of twist needed to stabilize a particular bullet. A little extra twist doesnt seem to hurt in most cases but im no br shooter. Let me ask you a question on the opposite end of the spectrum. Is there a baseline minimum bullet rpm to aim for, is it too dependent on caliber, type of bullet etc?

 

[roostercogburn98]

The 7.5 twist won't hurt ya. That's for sure. So if you go to 2910fps in a 7.5 twist... that puts you at 279,360rpm.

2910fps in a 7 twist.... that gives you 299,314rpm. You will be on borrowed time.

Again as you approach 300k and especially you start going past 300k... expect problems. Might not be at first but as soon as that throat area of the chamber starts getting rougher... the bullets will take more of a beating and the faster rpm isn't going to help anything. Some bullets might stand up to it and some might not. Again your on borrowed time.

Longer barrel... also generates more heat on the bullet due to friction... another factor that will play into it as well.

So an 18 inch 1-7.7 twist barrel with an average velocity of 2,730 gives me roughly 255,272 rpm.

Theoretically I should have a fairly healthy barrel life correct? I know things like rate of fire will have an impact as well, but just speaking rough terms.

 

[epeet]

7.5 is great. You can shoot 77s, 80s. I wouldn't sweat it. You may even see slightly better accuracy on 55s, which it sounds like you want.

 

[JerkyFreak]

How will the 80gr ELD-M's do out of a Tikka 1-8" twist?

 

[MarshallDodge]

I have 223s in several twist rates and really like the 1:8 as a good, all-around option. 1:7.5 might be a good choice as well.

The 1:8 barrel that I have is an 18" Bartlein, and I run everything from 52 grain match bullets to the 85 RDF.

 

[Frank Green]

Thanks Frank. Great information as always. It seems like the F class and benchrest guys lean towards the least amount of twist needed to stabilize a particular bullet. A little extra twist doesnt seem to hurt in most cases but im no br shooter. Let me ask you a question on the opposite end of the spectrum. Is there a baseline minimum bullet rpm to aim for, is it too dependent on caliber, type of bullet etc?

Yea... the BR guys...There #2 ranked on my wacky list. No offense to the BR guys... quite a few of them are friends of mine.

A little faster twist doesn't hurt you like some people think it might. Again good quality bullets / ammo with less runout in it... that's the key. For the most part regardless of caliber. Shoot shitty bullets or ammo that has a lot of runout in it... then with a faster twist you can see a negative accuracy wise.

There is no minimum baseline for bullet rpm to aim for etc... to my knowledge. Twist just has to be fast enough to properly stabilize it. For example... 308win. For the most part the standard twist of 1-12 will stabilize up to conventional 190gr bullets. Go heavier/longer bullets than you need a faster twist but a 175SMK out of a 12 twist won't shoot any better out of a 1-10 twist or a 8 twist etc...

Keep in mind that a lot of the newer non lead core solid bullets weight for weight vs a lead core bullet are typically longer o.a.l. on the solid bullets because they don't have the density of the lead core. It's bullet length that dictates twist more than anything else. Velocity does play a part but a small part.

I don't like running my stuff on the ragged edge twist wise like some of the BR guys do. You get in a colder temp, or your velocity is a little lower, conditions etc.... then your asking for accuracy issues as well. LB (customers initials) years ago (back around 1999) came out with his own bullets and was shooting them in his 6PPC and he shot 14 twist barrels. What he couldn't figure out was some days they pounded stupid small groups and other days.... the groups where horrible. His new bullets where longer than the old ones. He noticed it when the temps where cooler but when hot out... no issues. I told him to send me a couple and give me the velocity and I'd do a twist rate calc. I forget the exact number but I think the min. twist came in at 13.79 or something like that. I told him for his next barrels we go to a 13.5 twist instead of him getting 14's again. Bingo... he goes to Nationals that year and cleans every single class. That's how the 13.5 twist thing started in SR BR.

 

[Frank Green]

So an 18 inch 1-7.7 twist barrel with an average velocity of 2,730 gives me roughly 255,272 rpm.

Theoretically I should have a fairly healthy barrel life correct? I know things like rate of fire will have an impact as well, but just speaking rough terms.

I have yet to see any hard data that says twist rate has any bearing on barrel life.

Rate of fire, type of powder and type of bullet and case capacity size vs bore size are the driving factors.

 

[just browsing]

.219 bores are where it’s at for fast twist 223s. FTR guys have been messing with these things for years and have it figured out.

My current barrel is a 29” 1:7 and I’ve had zero failures even with 75s north of 3k. Hell I ran 55s up close to 3100 during break-in without issue.

Last barrel I had was a 25” .218 bore that would shed jackets on anything from 75 ELDs up to 90 VLDs, even at considerably slower speeds.